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MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps13668

Seagrass seed bank spatial structure and function following a large-scale decline

Jessie C. Jarvis*, Skye A. McKenna, Michael A. Rahseed

*Corresponding author:

ABSTRACT: We examined the spatial structure (distribution, density) and function (viability) of the seagrass sediment seed bank in the northern Great Barrier Reef World Heritage Area in Cairns Queensland following a large-scale decline in seagrass area. A spatially explicit seagrass seed bank analysis was paired with a long-term annual assessment of seagrass distribution to assess seed bank spatial patterns and their relationship with the recovery and presence of seagrass, and water depth. Four years post decline, the seed bank contained Zostera muelleri, Halodule uninervis, Halophila ovalis, and Cymodocea serrulata seeds. Seed banks reflected adjacent meadow community composition; however, the density of seeds for all recorded species was significantly lower than analogous seagrass populations, indicating a reduction in the capacity for recovery from the seed bank. A spatial structure existed in both the total (viable + non-viable) and viable seed bank, and distance between seed clusters ranged from 50-550 m depending on species or seed type. Observed patterns in clustering may be explained by variation in water depth and the past distribution of seagrass in these meadows. These results demonstrate that the distribution of seagrass seeds within the seed bank, which directly influences the natural recovery of seagrass communities, is not uniform across species and may result in patchy recovery of the meadows. Therefore, the resilience provided by the seed bank in seagrass communities should not be viewed as a static level of insurance for the entire meadow, but rather as dynamic and species-specific with variability over both space and time.